Hi, this Saturday, 25 July, from 1300-1500 GMT (2300-0100 AEST, 1400-1600 BST, 0900-1100 ET, 0600-0800 PT) I will be hosting the themed #seabirdersaturday on Twitter on using digital photography to measure egg colour.
Eggshell colouration can vary dramatically within and between bird species in terms of both background colour and maculation, or patterning. This has led to much research and several hypotheses being put forward to explain this variation including crypsis, structural strength, adaptation to brood parasitism, protection from solar radiation and signalling female quality or condition.
If egg colour can reflect information about female condition, and therefore about the local environment, then this could provide a relatively simple and cost-effective monitoring tool - especially if the information can be obtained quickly in the field using digital photography.
Unfortunately, it is not as straightforward as simply taking a photograph. I am no expert in this area, however, I will be tweeting about our experience of using digital photography to quantify the colour of herring gull eggs and the issues we came across. I will also cover some of the background of eggshell colouration, the pigments involved, uses of egg colour in other studies and any questions you might have.
So far questions I will cover include: • How we standardised taking photographs of eggs in the field • Setting the camera to account for taking photographs in different light conditions • How to extract colour information from digital photographs • How we dealt with non-linearity in the cameras response to light intensity • What other information can be extracted from egg photographs
PhD Student, University of Glasgow